High-resolution inductive array imaging of buried objects

Abstract

Despite ongoing research and development efforts, landmine and unexploded ordnance infestation continues to be a problem. Remediation efforts typically utilize inexpensive handheld metal detectors that rely on the principle of electromagnetic induction but have a limited depth of sensitivity and are unable to discriminate the shape, size, depth, and material type of the detected object. Conventional metal detectors can often detect all relevant metal objects. However, when instrument thresholds are set to a high level of sensitivity, unacceptably high false alarm rates result. To address these issues, a new design for inductive array detectors is under development. This design is founded on an advanced Nondestructive Evaluation (NDE) sensor called the MWM that was originally developed at MIT and has been successfully commercialized for manufacturing and NDE applications. The MWM-Array offers several advantages: (1) high resolution imaging with deep penetration, (2) varied applied field direction across sensor footprint, (3) potential for wide bandwidth continuous wave of pulsed mode operation, (4) simultaneous sampling and parallel processing of data form sensing element arrays for rapid image building, and (5) when measurements of the sensor element responses are combined with model-based measurement grids, quantitative estimates of size and depth for known object shapes can assist in the classification and discrimination of detected objects, as well as the elimination of false detections.